ABSTRACT
Spinal cord injury (SCI) results from various mechanisms that damage the nervous tissue and the blood-brain barrier, leading to sensory and motor function loss below the injury site. Unfortunately, current therapeutic approaches for SCI have limited efficacy in improving patients outcomes. Galectin-3, a protein whose expression increases after SCI, influences the neuroinflammatory response by favoring pro-inflammatory M1 macrophages and microglia, while inhibiting pro-regenerative M2 macrophages and microglia, which are crucial for inflammation resolution and tissue regeneration. Previous studies with Galectin-3 knock-out mice demonstrated enhanced motor recovery after SCI. The M1/M2 balance is strongly influenced by the predominant lymphocytic profiles (Th1, Th2, T Reg, Th17) and cytokines and chemokines released at the lesion site. The present study aimed to investigate how the absence of galectin-3 impacts the adaptive immune system cell population dynamics in various lymphoid spaces following a low thoracic spinal cord compression injury (T9-T10) using a 30 g vascular clip for one minute. It also aimed to assess its influence on the functional outcome in wild-type (WT)and Galectin-3 knock-out (GALNEG) mice. Histological analysis with hematoxylin-eosin and Luxol Fast Blue staining revealed that WT and GALNEG animals exhibit similar spinal cord morphology. The absence of galectin-3 does not affect the common neuroanatomy shared between the groups prompting us to analyze outcomes between both groups. Following our crush model, both groups lost motor and sensory functions below the lesion level. During a 42-day period, GALNEG mice demonstrated superior locomotor recovery in the Basso Mouse Scale (BMS) gait analysis and enhanced motor coordination performance in the ladder rung walk test (LRW) compared to WT mice. GALNEG mice also exhibited better sensory recovery, and their electrophysiological parameters suggested a higher number of functional axons with faster nerve conduction. Seven days after injury, flow cytometry of thymus, spleen, and blood revealed an increased number of T Reg and Th2 cells, accompanied by a decrease in Th1 and Th17 cells in GALNEG mice. Immunohistochemistry conducted on the same day exhibited an increased number of Th2 and T Reg cells around the GALNEG's spinal cord lesion site. At 42-day dpi immunohistochemistry analyses displayed reduced astrogliosis and greater axon preservation in GALNEG's spinal cord seem as a reduction of GFAP immunostaining and an increase in NFH immunostaining, respectively. In conclusion, GALNEG mice exhibited better functional recovery attributed to the milder pro-inflammatory influence, compensated by a higher quantity of T Reg and Th2 cells. These findings suggest that galectin-3 plays a crucial role in the immune response after spinal cord injury and could be a potential target for clinical therapeutic interventions.
Subject(s)
Galectin 3 , Mice, Inbred C57BL , Mice, Knockout , Recovery of Function , Spinal Cord Injuries , Animals , Spinal Cord Injuries/pathology , Spinal Cord Injuries/metabolism , Spinal Cord Injuries/physiopathology , Recovery of Function/physiology , Galectin 3/metabolism , Galectin 3/genetics , Mice , Lymphocytes/metabolism , Female , MaleABSTRACT
BACKGROUND: Traumatic spinal cord injury (SCI) is a disabling condition that affects millions of people around the world. Currently, no clinical treatment can restore spinal cord function. Comparison of molecular responses in regenerating to non-regenerating vertebrates can shed light on neural restoration. The axolotl (Ambystoma mexicanum) is an amphibian that regenerates regions of the brain or spinal cord after damage. METHODS: In this study, we compared the transcriptomes after SCI at acute (1-2 days after SCI) and sub-acute (6-7 days post-SCI) periods through the analysis of RNA-seq public datasets from axolotl and non-regenerating rodents. RESULTS: Genes related to wound healing and immune responses were upregulated in axolotls, rats, and mice after SCI; however, the immune-related processes were more prevalent in rodents. In the acute phase of SCI in the axolotl, the molecular pathways and genes associated with early development were upregulated, while processes related to neuronal function were downregulated. Importantly, the downregulation of processes related to sensorial and motor functions was observed only in rodents. This analysis also revealed that genes related to pluripotency, cytoskeleton rearrangement, and transposable elements (e.g., Sox2, Krt5, and LOC100130764) were among the most upregulated in the axolotl. Finally, gene regulatory networks in axolotls revealed the early activation of genes related to neurogenesis, including Atf3/4 and Foxa2. CONCLUSIONS: Immune-related processes are upregulated shortly after SCI in axolotls and rodents; however, a strong immune response is more noticeable in rodents. Genes related to early development and neurogenesis are upregulated beginning in the acute stage of SCI in axolotls, while the loss of motor and sensory functions is detected only in rodents during the sub-acute period of SCI. The approach employed in this study might be useful for designing and establishing regenerative therapies after SCI in mammals, including humans.
Subject(s)
Ambystoma mexicanum , Spinal Cord Injuries , Humans , Animals , Rats , Mice , Ambystoma mexicanum/genetics , RNA-Seq , Rodentia/genetics , Spinal Cord Injuries/genetics , Spinal Cord Injuries/metabolism , Gene Expression Profiling , Models, AnimalABSTRACT
Spinal cord injury (SCI) harms patients' health and social and economic well-being. Unfortunately, fully effective therapeutic strategies have yet to be developed to treat this disease, affecting millions worldwide. Apoptosis and autophagy are critical cell death signaling pathways after SCI that should be targeted for early therapeutic interventions to mitigate their adverse effects and promote functional recovery. Tibolone (TIB) is a selective tissue estrogen activity regulator (STEAR) with neuroprotective properties demonstrated in some experimental models. This study aimed to investigate the effect of TIB on apoptotic cell death and autophagy after SCI and verify whether TIB promotes motor function recovery. A moderate contusion SCI was produced at thoracic level 9 (T9) in male Sprague Dawley rats. Subsequently, animals received a daily dose of TIB orally and were sacrificed at 1, 3, 14 or 30 days post-injury. Tissue samples were collected for morphometric and immunofluorescence analysis to identify tissue damage and the percentage of neurons at the injury site. Autophagic (Beclin-1, LC3-I/LC3-II, p62) and apoptotic (Caspase 3) markers were also analyzed via Western blot. Finally, motor function was assessed using the BBB scale. TIB administration significantly increased the amount of preserved tissue (p < 0.05), improved the recovery of motor function (p < 0.001) and modulated the expression of autophagy markers in a time-dependent manner while consistently inhibiting apoptosis (p < 0.05). Therefore, TIB could be a therapeutic alternative for the recovery of motor function after SCI.
Subject(s)
Neuroprotective Agents , Spinal Cord Injuries , Humans , Rats , Male , Animals , Rats, Sprague-Dawley , Spinal Cord Injuries/metabolism , Apoptosis , Autophagy , Spinal Cord/metabolism , Recovery of Function , Neuroprotective Agents/pharmacology , Neuroprotective Agents/therapeutic use , Neuroprotective Agents/metabolismABSTRACT
In recent decades, an area of active research has supported the notion that progesterone promotes a wide range of remarkable protective actions in experimental models of nervous system trauma or disease, and has also provided a strong basis for considering this steroid as a promising molecule for modulating the complex maladaptive changes that lead to neuropathic pain, especially after spinal cord injury. In this review, we intend to give the readers a brief appraisal of the main mechanisms underlying the increased excitability of the spinal circuit in the pain pathway after trauma, with particular emphasis on those mediated by the activation of resident glial cells, the subsequent release of proinflammatory cytokines and their impact on N-methyl-D-aspartate receptor function. We then summarize the available preclinical data pointing to progesterone as a valuable repurposing molecule for blocking critical cellular and molecular events that occur in the dorsal horn of the injured spinal cord and are related to the development of chronic pain. Since the treatment and management of neuropathic pain after spinal injury remains challenging, the potential therapeutic value of progesterone opens new traslational perspectives to prevent central pain.
Subject(s)
Neuralgia , Spinal Cord Injuries , Humans , Progesterone/pharmacology , Receptors, N-Methyl-D-Aspartate/metabolism , Receptors, N-Methyl-D-Aspartate/therapeutic use , Neuroinflammatory Diseases , Hyperalgesia , Neuralgia/drug therapy , Neuralgia/etiology , Neuralgia/metabolism , Spinal Cord Injuries/complications , Spinal Cord Injuries/drug therapy , Spinal Cord Injuries/metabolism , Spinal Cord/metabolismABSTRACT
Neuropathic pain (NP) following a spinal cord injury (SCI) is often hard to control and therapies should be focused on the physical, psychological, behavioral, social, and environmental factors that may contribute to chronic sensory symptoms. Novel therapeutic treatments for NP management should be based on the combination of pharmacological and nonpharmacological options. Some of them are addressed in this review with a focus on mechanisms and novel treatments. Several reports demonstrated an aberrant expression of non-coding RNAs (ncRNAs) that may represent key regulatory factors with a crucial role in the pathophysiology of NP and as potential diagnostic biomarkers. This review analyses the latest evidence for cellular and molecular mechanisms associated with the role of circular RNAs (circRNAs) in the management of pain after SCI. Advantages in the use of circRNA are their stability (up to 48 h), and specificity as sponges of different miRNAs related to SCI and nerve injury. The present review discusses novel data about deregulated circRNAs (up or downregulated) that sponge miRNAs, and promote cellular and molecular interactions with mRNAs and proteins. This data support the concept that circRNAs could be considered as novel potential therapeutic targets for NP management especially after spinal cord injuries.
Subject(s)
MicroRNAs , Neuralgia , Spinal Cord Injuries , Humans , RNA, Circular/genetics , Pain Management , Spinal Cord Injuries/metabolism , MicroRNAs/genetics , Neuralgia/geneticsABSTRACT
Chronic, often intractable, pain is caused by neuropathic conditions such as traumatic peripheral nerve injury (PNI) and spinal cord injury (SCI). These conditions are associated with alterations in gene and protein expression correlated with functional changes in somatosensory neurons having cell bodies in dorsal root ganglia (DRGs). Most studies of DRG transcriptional alterations have utilized PNI models where axotomy-induced changes important for neural regeneration may overshadow changes that drive neuropathic pain. Both PNI and SCI produce DRG neuron hyperexcitability linked to pain, but contusive SCI produces little peripheral axotomy or peripheral nerve inflammation. Thus, comparison of transcriptional signatures of DRGs across PNI and SCI models may highlight pain-associated transcriptional alterations in sensory ganglia that do not depend on peripheral axotomy or associated effects such as peripheral Wallerian degeneration. Data from our rat thoracic SCI experiments were combined with meta-analysis of published whole-DRG RNA-seq datasets from prominent rat PNI models. Striking differences were found between transcriptional responses to PNI and SCI, especially in regeneration-associated genes (RAGs) and long noncoding RNAs (lncRNAs). Many transcriptomic changes after SCI also were found after corresponding sham surgery, indicating they were caused by injury to surrounding tissue, including bone and muscle, rather than to the spinal cord itself. Another unexpected finding was of few transcriptomic similarities between rat neuropathic pain models and the only reported transcriptional analysis of human DRGs linked to neuropathic pain. These findings show that DRGs exhibit complex transcriptional responses to central and peripheral neural injury and associated tissue damage. Although only a few genes in DRG cells exhibited similar changes in expression across all the painful conditions examined here, these genes may represent a core set whose transcription in various DRG cell types is sensitive to significant bodily injury, and which may play a fundamental role in promoting neuropathic pain.
Subject(s)
Neuralgia , Spinal Cord Injuries , Rats , Humans , Animals , Ganglia, Spinal/metabolism , Neuralgia/genetics , Neuralgia/metabolism , Spinal Cord Injuries/complications , Spinal Cord Injuries/genetics , Spinal Cord Injuries/metabolism , Spinal Cord/metabolism , Neurons/metabolismABSTRACT
Spinal cord injury (SCI) is a devastating traumatic condition accompanied with excessive inflammatory response and apoptosis of microglia. Long noncoding RNAs (lncRNAs) have been confirmed to be key regulators of cell inflammatory response. Nevertheless, the role of lncRNA KCNQ1OT1 in microglia apoptosis or inflammatory response after SCI remains to be explored. Our study focused on exploring the role and mechanism of KCNQ1OT1 in microglia after SCI. RT-qPCR showed that SCI induced the increase of KCNQ1OT1 level in mice spinal cord. Inhibition of KCNQ1OT1 suppressed the inflammatory response and apoptosis of microglia. In addition, KCNQ1OT1 was proved to bind with miR-589-5p, and NPTN was directly targeted by miR-589-5p. Furthermore, KCNQ1OT1 was negatively correlated with miR-589-5p and positively associated with NPTN. Rescue assays indicated that NPTN overexpression reversed the anti-inflammatory and anti-apoptosis effects of KCNQ1OT1 silencing. In summary, these data revealed that KCNQ1OT1 promoted inflammatory response and apoptosis of microglia by regulating the miR-589-5p/NPTN axis after SCI, which may offer a novel promising therapeutic target for SCI.
Subject(s)
MicroRNAs , RNA, Long Noncoding , Spinal Cord Injuries , Animals , Apoptosis/genetics , Mice , MicroRNAs/genetics , MicroRNAs/metabolism , Microglia/metabolism , RNA, Long Noncoding/genetics , RNA, Long Noncoding/metabolism , Spinal Cord Injuries/genetics , Spinal Cord Injuries/metabolismABSTRACT
Many people around the world suffer from some form of paralysis caused by spinal cord injury (SCI), which has an impact on quality and life expectancy. The spinal cord is part of the central nervous system (CNS), which in mammals is unable to regenerate, and to date, there is a lack of full functional recovery therapies for SCI. These injuries start with a rapid and mechanical insult, followed by a secondary phase leading progressively to greater damage. This secondary phase can be potentially modifiable through targeted therapies. The growing literature, derived from mammalian and regenerative model studies, supports a leading role for mitochondria in every cellular response after SCI: mitochondrial dysfunction is the common event of different triggers leading to cell death, cellular metabolism regulates the immune response, mitochondrial number and localization correlate with axon regenerative capacity, while mitochondrial abundance and substrate utilization regulate neural stem progenitor cells self-renewal and differentiation. Herein, we present a comprehensive review of the cellular responses during the secondary phase of SCI, the mitochondrial contribution to each of them, as well as evidence of mitochondrial involvement in spinal cord regeneration, suggesting that a more in-depth study of mitochondrial function and regulation is needed to identify potential targets for SCI therapeutic intervention.
Subject(s)
Spinal Cord Injuries , Spinal Cord Regeneration , Animals , Central Nervous System/metabolism , Humans , Mammals , Mitochondria/metabolism , Nerve Regeneration , Recovery of Function , Spinal Cord/metabolism , Spinal Cord Injuries/metabolism , Spinal Cord Regeneration/physiologyABSTRACT
Spinal cord injury (SCI) remains an important public health problem which often causes permanent loss of muscle strength, sensation, and function below the site of the injury, generating physical, psychological, and social impacts throughout the lives of the affected individuals, since there are no effective treatments available. The use of stem cells has been investigated as a therapeutic approach for the treatment of SCI. Although a significant number of studies have been conducted in pre-clinical and clinical settings, so far there is no established cell therapy for the treatment of SCI. One aspect that makes it difficult to evaluate the efficacy is the heterogeneity of experimental designs in the clinical trials that have been published. Cell transplantation methods vary widely among the trials, and there are still no standardized protocols or recommendations for the therapeutic use of stem cells in SCI. Among the different cell types, mesenchymal stem/stromal cells (MSCs) are the most frequently tested in clinical trials for SCI treatment. This study reviews the clinical applications of MSCs for SCI, focusing on the critical analysis of 17 clinical trials published thus far, with emphasis on their design and quality. Moreover, it highlights the need for more evidence-based studies designed as randomized controlled trials and potential challenges to be addressed in context of stem cell therapies for SCI.
Subject(s)
Mesenchymal Stem Cell Transplantation , Mesenchymal Stem Cells , Spinal Cord Injuries , Humans , Mesenchymal Stem Cell Transplantation/methods , Mesenchymal Stem Cells/metabolism , Spinal Cord Injuries/metabolism , Treatment OutcomeABSTRACT
The hippocampus encodes spatial and contextual information involved in memory and learning. The incorporation of new neurons into hippocampal networks increases neuroplasticity and enhances hippocampal-dependent learning performances. Only few studies have described hippocampal abnormalities after spinal cord injury (SCI) although cognitive deficits related to hippocampal function have been reported in rodents and even humans. The aim of this study was to characterize in further detail hippocampal changes in the acute and chronic SCI. Our data suggested that neurogenesis reduction in the acute phase after SCI could be due to enhanced death of amplifying neural progenitors (ANPs). In addition, astrocytes became reactive and microglial cells increased their number in almost all hippocampal regions studied. Glial changes resulted in a non-inflammatory response as the mRNAs of the major pro-inflammatory cytokines (IL-1ß, TNFα, IL-18) remained unaltered, but CD200R mRNA levels were downregulated. Long-term after SCI, astrocytes remained reactive but on the other hand, microglial cell density decreased. Also, glial cells induced a neuroinflammatory environment with the upregulation of IL-1ß, TNFα and IL-18 mRNA expression and the decrease of CD200R mRNA. Neurogenesis reduction may be ascribed at later time points to inactivation of neural stem cells (NSCs) and inhibition of ANP proliferation. The number of granular cells and CA1 pyramidal neurons decreased only in the chronic phase. The release of pro-inflammatory cytokines at the chronic phase might involve neurogenesis reduction and neurodegeneration of hippocampal neurons. Therefore, SCI led to hippocampal changes that could be implicated in cognitive deficits observed in rodents and humans.
Subject(s)
Neural Stem Cells , Spinal Cord Injuries , Hippocampus/metabolism , Humans , Neural Stem Cells/metabolism , Neurogenesis/physiology , Neuroglia/metabolism , Spinal Cord/metabolism , Spinal Cord Injuries/metabolismABSTRACT
After different types of acute central nervous system insults, including stroke, subarachnoid haemorrhage and traumatic brain and spinal cord injuries, secondary damage plays a central role in the induction of cell death, neurodegeneration and functional deficits. Interestingly, secondary cell death presents an attractive target for clinical intervention because the temporal lag between injury and cell loss provides a potential window for effective treatment. While primary injuries are the direct result of the precipitating insult, secondary damage involves the activation of pathological cascades through which endogenous factors can exacerbate initial tissue damage. Secondary processes, usually interactive and overlapping, include oxidative stress, neuroinflammation and dysregulation of autophagy, ultimately leading to cell death. Resveratrol, a natural stilbene present at relatively high concentrations in grape skin and red wine, exerts a wide range of beneficial health effects. Within the central nervous system, in addition to its inherent free radical scavenging role, resveratrol increases endogenous cellular antioxidant defences thus modulating multiple synergistic pathways responsible for its antioxidant, anti-inflammatory and anti-apoptotic properties. During the last years, a growing body of in vitro and in vivo evidence has been built, indicating that resveratrol can induce a neuroprotective state and attenuate functional deficits when administered acutely after an experimental injury to the central nervous system. In this review, we summarize the most recent findings on the molecular pathways involved in the neuroprotective effects of this multi target polyphenol, and discuss its neuroprotective potential after brain or spinal cord injuries.
Subject(s)
Anti-Inflammatory Agents/therapeutic use , Antioxidants/therapeutic use , Brain Injuries/drug therapy , Neuroprotective Agents/therapeutic use , Resveratrol/therapeutic use , Spinal Cord Injuries/drug therapy , Animals , Anti-Inflammatory Agents/pharmacology , Antioxidants/pharmacology , Brain Injuries/metabolism , Cell Death/drug effects , Cell Death/physiology , Humans , Neuroinflammatory Diseases/drug therapy , Neuroinflammatory Diseases/metabolism , Neuroprotective Agents/pharmacology , Oxidative Stress/drug effects , Oxidative Stress/physiology , Resveratrol/pharmacology , Spinal Cord Injuries/metabolismABSTRACT
The hippocampus is implicated in the generation of memory and learning, processes which involve extensive neuroplasticity. The generation of hippocampal adult-born neurons is particularly regulated by glial cells of the neurogenic niche and the surrounding microenvironment. Interestingly, recent evidence has shown that spinal cord injury (SCI) in rodents leads to hippocampal neuroinflammation, neurogenesis reduction, and cognitive impairments. In this scenario, the aim of this work was to evaluate whether an adenoviral vector expressing IGF1 could reverse hippocampal alterations and cognitive deficits after chronic SCI. SCI caused neurogenesis reduction and impairments of both recognition and working memories. We also found that SCI increased the number of hypertrophic arginase-1 negative microglia concomitant with the decrease of the number of ramified surveillance microglia in the hilus, molecular layer, and subgranular zone of the dentate gyrus. RAd-IGF1 treatment restored neurogenesis and improved recognition and working memory impairments. In addition, RAd-IGF1 gene therapy modulated differentially hippocampal regions. In the hilus and molecular layer, IGF1 gene therapy recovered the number of surveillance microglia coincident with a reduction of hypertrophic microglia cell number. However, in the neurogenic niche, IGF1 reduced the number of ramified microglia and increased the number of hypertrophic microglia, which as a whole expressed arginase-1. In summary, RAd-IGF1 gene therapy might surge as a new therapeutic strategy for patients with hippocampal microglial alterations and cognitive deficits such as those with spinal cord injury and other neurodegenerative diseases.
Subject(s)
Cognition/physiology , Cognitive Dysfunction/therapy , Genetic Therapy , Hippocampus/metabolism , Insulin-Like Growth Factor I/genetics , Neurogenesis/physiology , Spinal Cord Injuries/therapy , Animals , Cognitive Dysfunction/etiology , Cognitive Dysfunction/metabolism , Male , Microglia/metabolism , Neuronal Plasticity/physiology , Neurons/metabolism , Rats , Rats, Sprague-Dawley , Spinal Cord Injuries/complications , Spinal Cord Injuries/metabolismABSTRACT
The cytoskeleton of ependymal cells is fundamental to organize and maintain the normal architecture of the central canal (CC). However, little is known about the plasticity of cytoskeletal components after spinal cord injury. Here, we focus on the structural organization of the cytoskeleton of ependymal cells in the normal and injured spinal cord of mice (both females and males) using immunohistochemical and electron microscopy techniques. We found that in uninjured animals, the actin cytoskeleton (as revealed by phalloidin staining) was arranged following the typical pattern of polarized epithelial cells with conspicuous actin pools located in the apical domain of ependymal cells. Transmission electron microscopy images showed microvilli tufts, long cilia, and characteristic intercellular membrane specializations. After spinal cord injury, F-actin rearrangements paralleled by fine structural modifications of the apical domain of ependymal cells were observed. These changes involved disruptions of the apical actin pools as well as fine structural modifications of the microvilli tufts. When comparing the control and injured spinal cords, we also found modifications in the expression of vimentin and glial fibrillary acidic protein (GFAP). After injury, vimentin expression disappeared from the most apical domains of ependymal cells but the number of GFAP-expressing cells within the CC increased. As in other polarized epithelia, the plastic changes in the cytoskeleton may be critically involved in the reaction of ependymal cells following a traumatic injury of the spinal cord.
Subject(s)
Cytoskeleton/metabolism , Ependyma/metabolism , Spinal Cord Injuries/metabolism , Spinal Cord/metabolism , Thoracic Vertebrae/injuries , Animals , Cytoskeleton/pathology , Ependyma/cytology , Ependyma/pathology , Female , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Spinal Cord/cytology , Spinal Cord/pathology , Spinal Cord Injuries/pathologyABSTRACT
Spinal cord injury (SCI) is a complex neuropathological condition that represents a major challenge for clinicians and scientists due to patient's functional dysfunction and paralysis. Several treatments have been proposed including biological factors, drugs and cells administered in various ways. Stem cells arise as good candidates to treat SCI since they are known to secrete neurotrophic factors, improving neuroregeneration, but also due to their role in modulating the inflammatory process, favoring a pro-regenerative status. There are several types of cells that have been tested to treat SCI in experimental and clinical studies, but we still face many unanswered questions; one of them is the type of cells that can offer the best benefits and, also the ideal dose and administration routes. This review aimed to summarize recent research on cell treatment, focusing on current delivery strategies for SCI therapy and their effects in tissue repair and regeneration.
Subject(s)
Neurogenesis , Spinal Cord Injuries/surgery , Spinal Cord Regeneration , Spinal Cord/surgery , Stem Cell Transplantation , Animals , Humans , Recovery of Function , Spinal Cord/metabolism , Spinal Cord/pathology , Spinal Cord/physiopathology , Spinal Cord Injuries/metabolism , Spinal Cord Injuries/pathology , Spinal Cord Injuries/physiopathology , Stem Cell Transplantation/adverse effects , Treatment OutcomeABSTRACT
Correct operation of neuronal networks depends on the interplay between synaptic excitation and inhibition processes leading to a dynamic state termed balanced network. In the spinal cord, balanced network activity is fundamental for the expression of locomotor patterns necessary for rhythmic activation of limb extensor and flexor muscles. After spinal cord lesion, paralysis ensues often followed by spasticity. These conditions imply that, below the damaged site, the state of balanced networks has been disrupted and that restoration might be attempted by modulating the excitability of sublesional spinal neurons. Because of the widespread expression of inhibitory GABAergic neurons in the spinal cord, their role in the early and late phases of spinal cord injury deserves full attention. Thus, an early surge in extracellular GABA might be involved in the onset of spinal shock while a relative deficit of GABAergic mechanisms may be a contributor to spasticity. We discuss the role of GABA A receptors at synaptic and extrasynaptic level to modulate network excitability and to offer a pharmacological target for symptom control. In particular, it is proposed that activation of GABA A receptors with synthetic GABA agonists may downregulate motoneuron hyperexcitability (due to enhanced persistent ionic currents) and, therefore, diminish spasticity. This approach might constitute a complementary strategy to regulate network excitability after injury so that reconstruction of damaged spinal networks with new materials or cell transplants might proceed more successfully.
Subject(s)
Excitatory Postsynaptic Potentials/physiology , Inhibitory Postsynaptic Potentials/physiology , Nerve Net/metabolism , Receptors, GABA-A/metabolism , Spinal Cord Injuries/metabolism , Spinal Cord/metabolism , Animals , GABAergic Neurons/physiology , Humans , Motor Neurons/metabolism , Motor Neurons/pathology , Nerve Net/pathology , Spinal Cord/pathology , Spinal Cord Injuries/physiopathologyABSTRACT
Axonal damage is an early step in traumatic and neurodegenerative disorders of the central nervous system (CNS). Damaged axons are not able to regenerate sufficiently in the adult mammalian CNS, leading to permanent neurological deficits. Recently, we showed that inhibition of the autophagic protein ULK1 promotes neuroprotection in different models of neurodegeneration. Moreover, we demonstrated previously that axonal protection improves regeneration of lesioned axons. However, whether axonal protection mediated by ULK1 inhibition could also improve axonal regeneration is unknown. Here, we used an adeno-associated viral (AAV) vector to express a dominant-negative form of ULK1 (AAV.ULK1.DN) and investigated its effects on axonal regeneration in the CNS. We show that AAV.ULK1.DN fosters axonal regeneration and enhances neurite outgrowth in vitro. In addition, AAV.ULK1.DN increases neuronal survival and enhances axonal regeneration after optic nerve lesion, and promotes long-term axonal protection after spinal cord injury (SCI) in vivo. Interestingly, AAV.ULK1.DN also increases serotonergic and dopaminergic axon sprouting after SCI. Mechanistically, AAV.ULK1.DN leads to increased ERK1 activation and reduced expression of RhoA and ROCK2. Our findings outline ULK1 as a key regulator of axonal degeneration and regeneration, and define ULK1 as a promising target to promote neuroprotection and regeneration in the CNS.
Subject(s)
Autophagy-Related Protein-1 Homolog/metabolism , Axons/metabolism , Dependovirus/genetics , Gene Transfer Techniques , Genetic Vectors , Nerve Regeneration , Optic Nerve Injuries/therapy , Optic Nerve/metabolism , Spinal Cord Injuries/therapy , Spinal Cord/metabolism , Animals , Autophagy-Related Protein-1 Homolog/genetics , Axons/pathology , Cells, Cultured , Disease Models, Animal , Dopaminergic Neurons/metabolism , Dopaminergic Neurons/pathology , Down-Regulation , Female , Mitogen-Activated Protein Kinase 3/metabolism , Neuronal Outgrowth , Optic Nerve/pathology , Optic Nerve Injuries/genetics , Optic Nerve Injuries/metabolism , Optic Nerve Injuries/pathology , Rats, Wistar , Serotonergic Neurons/metabolism , Serotonergic Neurons/pathology , Spinal Cord/pathology , Spinal Cord Injuries/genetics , Spinal Cord Injuries/metabolism , Spinal Cord Injuries/pathology , Time Factors , rho GTP-Binding Proteins/metabolism , rho-Associated Kinases/metabolismABSTRACT
OBJECTIVE: To observe the seminal plasma proteomic composition in men with spinal cord injury orally treated with probenecid, in order to observe pathways associated with increased sperm motility. STUDY DESIGN: Prospective study. SETTING: Miami Project to Cure Paralysis - University of Miami/Miller School of Medicine. PARTICIPANTS: Nine men with spinal cord injury, who agreed to participate in the study. INTERVENTION: Oral treatment with probenecid - 500â mg per day for one week, then 500â mg twice daily [1000â mg total] per day for three weeks. OUTCOME MEASURES: Semen analysis as per WHO 2010 guidelines, and seminal plasma proteomics analysis by LC-MS/MS. RESULTS: In total, 783 proteins were identified, of which, 17 were decreased, while 6 were increased after treatment. The results suggest a new pathway that could be treated by the decrease of biglycan after probenecid treatment. CONCLUSION: Oral treatment with probenecid is able to alter the seminal plasma proteome, in pathways that explain decreased innate immune response.
Subject(s)
Semen , Spinal Cord Injuries , Chromatography, Liquid , Humans , Male , Probenecid/pharmacology , Probenecid/therapeutic use , Prospective Studies , Proteomics/methods , Semen/metabolism , Sperm Motility/physiology , Spermatozoa/metabolism , Spinal Cord Injuries/drug therapy , Spinal Cord Injuries/metabolism , Tandem Mass SpectrometryABSTRACT
The skeletal muscle mass reduces 30-60% after spinal cord injury, this is mostly due to protein degradation through ubiquitin-proteasome system. In this work, we propose that the flavanol (-)-epicatechin, due its widespread biological effects on muscle health, can prevent muscle mass decrease after spinal cord injury. Thirty-six female Long Evans rats were randomized into 5 groups: (1) Spinal cord injury 7 days, (2) Spinal cord injury + (-)-epicatechin 7 days, (3) Spinal cord injury 30 days, (4) Spinal cord injury + (-)-epicatechin 30 days and (5) Sham (Only laminectomy). Hind limb perimeter, muscle cross section area, fiber cross section area and ubiquitin-proteasome system protein expression together with total protein ubiquitination were assessed. At 30 days Spinal cord injury group lost 49.52 ± 2.023% of muscle cross section area (-)-epicatechin treated group lost only 24.28 ± 15.45% being a significant difference. Ubiquitin-proteasome markers showed significant changes. FOXO1a increased in spinal cord injury group vs Sham (-)-epicatechin reduced this increase. In spinal cord injury group MAFbx increased significantly vs Sham but decrease in (-)-epicatechin treatment group at 30 days. At 7 and 30 days MuRF1 increased in the spinal cord injury and decreased in the (-)-epicatechin group. The global protein ubiquitination increases after spinal cord injury, epicatechin treatment induce a significant decrease in protein ubiquitination. These results suggest that (-)-epicatechin reduces the muscle waste after spinal cord injury through down regulation of the ubiquitin-proteasome system.
Subject(s)
Catechin/pharmacology , Disease Models, Animal , Muscle, Skeletal/drug effects , Proteasome Endopeptidase Complex/metabolism , Spinal Cord Injuries/metabolism , Animals , Female , Magnetic Resonance Imaging/methods , Muscle, Skeletal/metabolism , Muscle, Skeletal/pathology , Muscular Atrophy/diagnostic imaging , Muscular Atrophy/metabolism , Muscular Atrophy/prevention & control , Myofibrils/metabolism , Rats, Long-Evans , Spinal Cord Injuries/pathologyABSTRACT
The immunosuppressant drug FK506 (or tacrolimus) is a macrolide that binds selectively to immunophilins belonging to the FK506-binding protein (FKBP) subfamily, which are abundantly expressed proteins in neurons of the peripheral and central nervous systems. Interestingly, it has been reported that FK506 increases neurite outgrowth in cell cultures, implying a potential impact in putative treatments of neurodegenerative disorders and injuries of the nervous system. Nonetheless, the mechanism of action of this compound is poorly understood and remains to be elucidated, with the only certainty that its neurotrophic effect is independent of its primary immunosuppressant activity. In this study it is demonstrated that FK506 shows efficient neurotrophic action in vitro and profound effects on the recovery of locomotor activity, behavioural features, and erectile function of mice that underwent surgical spinal cord injury. The recovery of the locomotor activity was studied in knock-out mice for either immunophilin, FKBP51 or FKBP52. The experimental evidence demonstrates that the neurotrophic actions of FK506 are the consequence of its binding to FKBP52, whereas FK506 interaction with the close-related partner immunophilin FKBP51 antagonises the function of FKBP52. Importantly, our study also demonstrates that other immunophilins do not replace FKBP52. It is concluded that the final biological response is the resulting outcome of the drug binding to both immunophilins, FKBP51 and FKBP52, the latter being the one that commands the dominant neurotrophic action in vivo.
Subject(s)
Nerve Regeneration/drug effects , Spinal Cord Injuries/drug therapy , Spinal Cord Injuries/metabolism , Tacrolimus Binding Proteins/metabolism , Tacrolimus/metabolism , Tacrolimus/therapeutic use , Animals , Cell Line, Tumor , Cells, Cultured , Male , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Mice, Knockout , Nerve Regeneration/physiology , Protein BindingABSTRACT
BACKGROUND: Spinal cord injury (SCI) is a severe central nervous system trauma. The present study aimed to evaluate the effect of HIF-1α on inflammation in spinal cord injury (SCI) to uncover the molecular mechanisms of anti-inflammation. RESULTS: HIF-1α was reduced in SCI model rats and HIF-1α activation reduced TNF-α, IL-1ß, IL-6 and IL-18 levels in SCI model rats. Meanwhile, Circ 0001723 expression was down-regulated and miR-380-3p expression was up-regulated in SCI model rats. In vitro model, down-regulation of Circ 0001723 promoted TNF-α, IL-1ß, IL-6 and IL-18 levels, compared with control negative group. However, over-expression of Circ 0001723 reduced TNF-α, IL-1ß, IL-6 and IL-18 levels in vitro model. Down-regulation of Circ 0001723 suppressed HIF-1α protein expressions and induced NLRP3 and Caspase-1 protein expressions in vitro model by up-regulation of miR-380-3p. Next, inactivation of HIF-1α reduced the pro-inflammation effects of Circ 0001723 in vitro model. Then, si-NLRP3 also inhibited the pro-inflammation effects of Circ 0001723 in vitro model via promotion of autophagy. CONCLUSIONS: We concluded that HIF-1α reduced inflammation in spinal cord injury via miR-380-3p/ NLRP3 by Circ 0001723.